These days she's a champion for climate change activism as the founder of one of Australia's largest environmental movements, 1 Million Women. But she wasn't always so concerned about sustainability.

Isaacs sheepishly admits that up until a few years ago she never thought about the environment, didn't worry too much about recycling and - oh, the horror - got around in a petrol-guzzling four-wheel-drive.

''I was bad,'' she confesses from her home in Newport. ''I had a giant four-wheel-drive. I never caught the bus, ever. It never occurred to me that I should catch the bus.

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''I never thought about food waste. I just did not care. I bought things on impulse. I never went to a second-hand store. It never occurred to me that I could or even should live in a much more sustainable way.''

Like many busy women, she thought living sustainably was all too hard. And what difference could she make on an individual level, anyway? Then one day in 2006, the light bulb - no doubt a low-emission one - switched on.

''I finally got it,'' she recalls. ''I realised the way I was living was not just expensive but completely unsustainable.''

She started taking small steps at home. The 4WD was sold and replaced with a bus ticket, although she concedes that public transport on the northern beaches is ''not fantastic''. Appliances were routinely switched off at the outlet. Reusable shopping bags replaced plastic ones. Shopping lists were planned precisely to reduce wastage and worm farms were brought in for the scraps.

Before too long, the mother of four started to see results. ''I got my electricity bill down by 20 per cent, I got my food waste down by 50 per cent,'' she said. ''Once I started to take action in my own life and see a tangible result, I took ownership of it.''

Isaacs decided to spread the word to other women, which is how 1 Million Women was born in 2009.

''I thought there must be millions of women out there who were just like me,'' she said. ''They might be aware of climate change but they were not engaged with it and not acting. They were probably thinking, as I used to, 'What's the point, I'm only one person, so who cares? Does it really matter what I do?' But it actually does.''

An aromatherapist who ran her own business, she created the website 1millionwomen.com.au aimed at advising women how to reduce their carbon footprint. The goal, for those who sign up, is to reduce their carbon emissions by one tonne in a year.

The 1 Million Women website provides free tips on how to save energy and reduce waste in areas such as food preparation, appliances, shopping, transport, clothing and home design.